Author Topic: Rehydration/wort temperature  (Read 1102 times)

Offline WyBrewer

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Rehydration/wort temperature
« on: September 25, 2015, 12:38:42 AM »
Hello all, new brewer here.  I have read that wort should be cooled to close to fermentation temperatures (a couple of degrees below, actually), that rehydrated dry yeast should be sprinkled into pre-boiled water that is around 100 degrees F, and that the rehydrated yeast should be about the same temperature as the wort when it is pitched, and that it is best when it is pitched within 30 minutes of being rehydrated.  What is the best way to get the rehydrated yeast slurry down to fermentation temps? This is for ales, which I am fermenting in my basement at about 63 degrees F. I have been cooling the slurry container in a cold water bath, but have had some lag in fermentation, and am wondering whether there is a better way.

Thanks for any help you can provide.
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Offline breweite

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Re: Rehydration/wort temperature
« Reply #1 on: September 25, 2015, 01:47:12 AM »
If I was worried about rehydrated dry yeast being too warm for my wort, I would use a wine thief and slowly add a little cooled wort a few drops at a time, not too much to shock the yeast.  Eventually, I'd bring the ~100F solution down to the wort's temperature.. This is definitely an extra step and takes a little time and good sanitation practices... but a war could be started if I bring up hydrating or not when it comes to dry yeast. 

BUT, nothing wrong with bringing it closer to wort temps!  Sounds desirable to me, if I were yeast...
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Offline Three

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Re: Rehydration/wort temperature
« Reply #2 on: September 25, 2015, 04:25:35 AM »
Not sure what yeast your using.  This is from Fermentis for their ale yeasts.   80 degrees is plenty warm enough to rehydrate.  After 30 minutes it should be cool enough to pitch. OR pitch dry per their instructions as well.   The only time I rehydrate is when I ferment in a carboy.  Easier to pitch.  In a bucket, I sprinkle it on dry and close her up...


rehydration instructions
Sprinkle the yeast in minimum 10 times its weight of sterile water or wort at 27°C ± 3°C (80°F ± 6°F). Leave to rest 15 to 30 minutes.
Gently stir for 30 minutes, and pitch the resultant cream into the fermentation vessel.
Alternatively, pitch the yeast directly in the fermentation vessel providing the temperature of the wort is above 20°C (68°F). Progressively sprinkle
the dry yeast into the wort ensuring the yeast covers all the surface of wort available in order to avoid clumps. Leave for 30 minutes, then mix the
wort using aeration or by wort addition.

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Offline erockrph

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Re: Rehydration/wort temperature
« Reply #3 on: September 25, 2015, 01:55:34 PM »
I gave up rehydrating a long time ago since my beers were turning out just as good when I just sprinkled my dry yeast on top of my wort.

How much lag are you seeing, and (much more importantly), how are your beers turning out? Dry yeast does tend to have a bit longer of a lag time than a fresh starter of liquid yeast, but as long as your sanitation is good that shouldn't really have an impact on the finished beer.
Eric B.

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Offline Todd H.

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Re: Rehydration/wort temperature
« Reply #4 on: September 25, 2015, 02:06:34 PM »
For US-05, I've rehydrated towards the end of mash in a 1 qt mason jar, and after ~30 minutes added ~1 cup of wort from the beginning of the boil (cooled, of course).  By the time the wort was cooled the yeast was active, and once pitched, fermentation visibly active in 3h.
Never did a side by side comparison with conventionally rehydrated yeast so I can't say if it had an impact on flavor or anything, though.  Still, I thought it was interesting that I essentially got zero lag time.

Offline WyBrewer

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Re: Rehydration/wort temperature
« Reply #5 on: September 26, 2015, 10:39:20 PM »
Thanks for the replies.  The lag varies with the type of yeast, some seem ok, and some seem to take a full day or two to get going.  I am doing 1 gallon batches by the way.  One type, I think it was Safbrew T-58, produced very little activity the first 2 days, and then quit altogether.  I roused the yeast by gently rocking the closed fermenter and it soon began bubbling through the airlock again.  I may be worrying too much, as the beer turns out pretty good, but as I am new to this, I just wondered what other brewers were doing.  The books I have read (The Complete Joy of Homebrewing and How to Brew) recommend rehydrating; I had not considered pitching it dry, maybe I'll try that next time. 
Good judgment is the result of experience and experience the result of bad judgment.
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Offline denny

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Re: Rehydration/wort temperature
« Reply #6 on: September 27, 2015, 12:01:38 AM »
If you're putting an entire pack of dry yeast into 1 gal. and fermenting at room temp, it's possible that fermentation is done in a few hours and you missed it!  The CO2 release you see from the airlock when shaking is evidnce that it's fermented.  That's dissloved CO2 coming out of solution.  I seldom rehydrate dry yeast for a 5.5 gal. batch and get fine results.  In a one gal. batch, it's completely unnecessary.  But if you do it right, it can't hurt either.  Me, I don't like doing things that don't pay off indemonstrably better beer, so I wouldn't bother.
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Offline Werks21

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Re: Rehydration/wort temperature
« Reply #7 on: October 04, 2015, 08:45:55 PM »
+ one for skipping yeast hydration step.

The first time I used dry yeast I was skeptical of it to begin with but following the advice of local home brew shop employee I gave it a shot without hydration before hand. It went into a 10 gallon batch of porter which had to go into two carboys anyway so I pitted a pack of S-05 against a smack pack of 1056, both with no starters and could not tell the difference between the beers, nor could several of my friends with somewhat beer savy pallets.
Jonathan W.
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evil_morty

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Re: Rehydration/wort temperature
« Reply #8 on: October 05, 2015, 10:41:32 AM »
I used to always rehydrate.  First in wort per "how to brew" then in water when I found out that was the better way to go.  Then in slightly warmer water (90ish F) when I found out that was supposed to be better.  Then Denny convinced me to try not rehydrating at all (which I had never done) and the beer was just as good if not better.  So now I skip it and just sprinkle room temp dry yeast into properly chilled wort.

Offline f.stepanski

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Re: Rehydration/wort temperature
« Reply #9 on: October 23, 2015, 01:18:10 AM »
I rehydrate in a double boiler..  I fill a large cast iron skillet 3/4 or so with water, inside that I set a glass bowl, boil for 10 mins or so..  Then pour out most of liquid from both, leave the glass bowl inside the skillet surrounded with water.  I wait for the entire lot to cool to 100F then pitch my dry yeast.  I allow the glass bowl to sit in the cast iron skillet surrounded with water, laws of thermal mass, takes a long time for this to cool; ergo I give the yeast plenty of time to rehydrate in a warm environment..  After 20-30 mins I remove the glass bowl & allow to cool to room temp.  Once cooled I pitch..  Have had good fermentations with this process..
« Last Edit: October 23, 2015, 01:22:27 AM by f.stepanski »
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